A New Method for Evaluating Moisture Content and Aging Degree of Transformer Oil-Paper Insulation Based on Frequency Domain Spectroscopy

Xia, Guoqiang; Wu, Guangning; Gao, Bo; Yin, Haojie; Yang, Feibao

doi:10.3390/en10081195

Cited by 28 publications

(20 citation statements)

References 26 publications

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“…Comparing dielectric responses with those recorded from standardized samples, also known as "fingerprints", to present qualitative knowledge of the insulation state [13][14][15]; • Modeling the OIP system to match the responses to thereby understand the dependence of model parameters on insulation conditions [11,[16][17][18][19][20]; • Deriving numerical characteristics from the traces and fitting with intuitional indicators, e.g., moisture percentage or the degree of polymerization (DP) to develop analytical formulas between them [10,[21][22][23].…”

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confidence: 99%

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A Parameterization Approach for the Dielectric Response Model of Oil Paper Insulation Using FDS Measurements

Feng

Yang

et al. 2018

Energies

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Abstract:To facilitate better interpretation of dielectric response measurements-thereby directing numerical evidence for condition assessments of oil-paper-insulated equipment in high-voltage alternating current (HVAC) transmission systems-a novel approach is presented to estimate the parameters in the extended Debye model (EDM) using wideband frequency domain spectroscopy (FDS). A syncretic algorithm that integrates a genetic algorithm (GA) and the Levenberg-Marquardt (L-M) algorithm is introduced in the present study to parameterize EDM using the FDS measurements of a real-life 126 kV oil-impregnated paper (OIP) bushing under different controlled temperatures. As for the uncertainty of the EDM structure due to variable branch quantity, Akaike's information criterion (AIC) is employed to determine the model orders. For verification, comparative analysis of FDS reconstruction and results of FDS transformation to polarization-depolarization current (PDC)/return voltage measurement (RVM) are presented. The comparison demonstrates good agreement between the measured and reconstructed spectroscopies of complex capacitance and tan δ over the full tested frequency band (10 −4 Hz-10 3 Hz) with goodness of fit over 0.99. Deviations between the tested and modelled PDC/RVM from FDS are then discussed. Compared with the previous studies to parameterize the model using time domain dielectric responses, the proposed method solves the problematic matching between EDM and FDS especially in a wide frequency band, and therefore assures a basis for quantitative insulation condition assessment of OIP-insulated apparatus in energy systems.

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confidence: 99%

“…To solve this problem, parameterizing EDM directly using FDS instead of PDC or RVM should therefore be carefully addressed, because a wideband FDS, as mentioned earlier [10,11], features better anti-interference and high-frequency precision, making it more suitable for parameter identification. Unfortunately, use of FDS in practice has rarely been reported.…”

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confidence: 99%

A Parameterization Approach for the Dielectric Response Model of Oil Paper Insulation Using FDS Measurements

Feng

Yang

et al. 2018

Energies

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“…On the contrary, the dielectric response technique, which serves as one of the most predominant techniques in the insulation condition diagnosis field, is also classified into the time-domain response and the frequency-domain response. Compared to the frequency-domain response (FDR), the time-domain response (TDR) has been suggested to have several defects including poor anti-interference and high time-consumption; the FDR is, therefore, believed to be more interesting for researchers [8,[14][15][16].…”

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confidence: 99%

Prediction of Moisture and Aging Conditions of Oil-Immersed Cellulose Insulation Based on Fingerprints Database of Dielectric Modulus

Zhang

Fan

et al. 2020

Polymers

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Frequency-domain spectroscopy (FDS) is demonstrated to be affected by electrode polarization and conductance behavior in the low-frequency ranges, which causes the unreliable prediction results of transformer cellulose insulation. In order to solve this issue, a fingerprint database based on the dielectric modulus is reported to predict the degree of polymerization (DP) and moisture content of cellulose insulation. In the current work, the relevant fingerprints that characterize the insulation conditions are obtained by studying the dielectric modulus curves of cellulose insulation with various insulation conditions, as well as the DC conductivity of transformer oil. Then, the dielectric modulus fingerprint database is established in the lab, and the accuracy of the reported fingerprint database is later verified. As a potential tool, the dielectric modulus fingerprint database is tested by several samples, and the results demonstrate that the accuracy of this method is more than 80%. In that respect, an interesting discovery of this paper is that the dielectric modulus fingerprint database may be a helpful tool for conditions prediction of the transformer cellulose insulation system.

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“…Moisture in cellulose insulation is a very serious operational threat to transformers. Moisture reduces insulation material resistivity [13] and dielectric strength [14] which decreases the partial discharge inception voltage and increases transformer failure probability [15][16][17][18][19][20][21]. In addition, moisture increases dielectric losses in cellulose insulation [22,23], which increases its temperature and thus shortens its lifetime.…”

Section: Introductionmentioning

confidence: 99%

Application of Synthetic Ester for Drying Distribution Transformer Insulation—The Influence of Cellulose Thickness on Drying Efficiency

et al. 2019

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A high level of insulation moisture in a transformer increases the breakdown probability and forces a reduction of its load. Therefore, there is a need to dry the transformer insulation. For technical reasons, there are some restrictions on the use of common drying methods for cellulose insulation available on the market. The aim of the research was to check the possibility of using synthetic ester for effective drying of cellulose materials of various thickness and an evaluation of the drying dynamics. The replacement of mineral oil with a synthetic ester caused a reduction of moisture in paper and thin pressboard by one percentage point. It was possible in the case of drying these materials for seven days at a temperature of 70 °C. The effects of drying were much smaller in the case of thicker cellulose samples. This paper also shows the complex problem of simultaneously drying materials of different thicknesses. Drying thin paper and thick pressboard at the same time significantly slows down the drying process of the pressboard. Presented results will be used to develop a procedure for drying the transformer insulation system using a synthetic ester.

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A New Method for Evaluating Moisture Content and Aging Degree of Transformer Oil-Paper Insulation Based on Frequency Domain Spectroscopy

Cited by 28 publications

References 26 publications

A Parameterization Approach for the Dielectric Response Model of Oil Paper Insulation Using FDS Measurements

A Parameterization Approach for the Dielectric Response Model of Oil Paper Insulation Using FDS Measurements

Prediction of Moisture and Aging Conditions of Oil-Immersed Cellulose Insulation Based on Fingerprints Database of Dielectric Modulus

Application of Synthetic Ester for Drying Distribution Transformer Insulation—The Influence of Cellulose Thickness on Drying Efficiency

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